A mother good enough is the one who takes care of her child as much as she can. In order for the child to develop in a healthy way it needs to feel safe, seen- it knows you care and pay attention to its life, soothed - it knows you will be there for him/her if it is hurting, secure - feels like that because of having all of the previous three, then it means you are a mother good enough.
If you think of yourself as a “bad” mother
If the feeling of guilt crosses your mind way too often
If you second guess yourself as a mother way too many times
If you feel a big pressure from your family, friends, the society